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The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

Publication ,  Journal Article
Nace, TE; Baker, PA; Dwyer, GS; Silva, CG; Rigsby, CA; Burns, SJ; Giosan, L; Otto-Bliesner, B; Liu, Z; Zhu, J
Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
December 1, 2014

Reconstructions of surface paleoceanographic conditions of the western equatorial Atlantic and past climates of the adjacent Northeast Brazilian (the "Nordeste") continental margin were undertaken by analyzing sediments from a piston core and associated gravity and box cores recovered from 3107 meter water depth at 0° 20' N on the equatorial Brazilian continental slope. The record is dated by radiocarbon analysis and oxygen isotopic stratigraphy of planktonic foraminifers and spans from near-modern to approximately 110 Ka.High-resolution XRF analysis provides insight into the paleoclimate history of the Nordeste during the last glacial interval. Several large-amplitude and abrupt peaks are observed in the time series of Ti/Ca and are usually accompanied by peaks of Fe/K. Together these record periods of increased precipitation and intense weathering on the adjacent continent and increased terrestrial sediment discharge from Nordeste rivers into the Atlantic. Within the limits of dating accuracy, most Ti/Ca peaks correlate with Heinrich events in the North Atlantic. This record thus corroborates, and extends back in time, the previous record of Arz et al. (1998) determined on sediment cores from farther southeast along the Nordeste margin.Stable oxygen isotopic analysis and Mg/Ca paleothermometry on the near-surface-dwelling planktonic foraminiferal species Globierinoides ruber find that mean sea-surface temperature (SST) during glacial time (20-55 Ka, n. =. 97) was 23.89. ±. 0.79. °C and the mean SST during the late Holocene (0-5 Ka, n. =. 14) was 26.89. ±. 0.33. °C. SSTs were 0.5-2. °C higher and inferred sea-surface salinities were lower during most of the periods of elevated Ti/Ca, thus, as observed in previous studies, the western equatorial Atlantic was warm (at least locally) and the adjacent southern tropical continent was wet at the same time that the high-latitude North Atlantic was cold.Using the SYNTRACE-CCSM3 fully coupled climate model with transient forcing for the period 22 Ka to present, we find that decreased transport of the North Brazil Current co-occurs with reduced Atlantic meridional overturning circulation, and colder-than-normal SSTs in the North Atlantic region. These simulated conditions are invariably associated with significantly increased precipitation in the Nordeste region.

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Published In

Palaeogeography, Palaeoclimatology, Palaeoecology

DOI

ISSN

0031-0182

Publication Date

December 1, 2014

Volume

415

Start / End Page

3 / 13

Related Subject Headings

  • Paleontology
  • 4301 Archaeology
  • 3709 Physical geography and environmental geoscience
  • 0603 Evolutionary Biology
  • 0602 Ecology
  • 0403 Geology
 

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Nace, T. E., Baker, P. A., Dwyer, G. S., Silva, C. G., Rigsby, C. A., Burns, S. J., … Zhu, J. (2014). The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary. Palaeogeography, Palaeoclimatology, Palaeoecology, 415, 3–13. https://doi.org/10.1016/j.palaeo.2014.05.030
Nace, T. E., P. A. Baker, G. S. Dwyer, C. G. Silva, C. A. Rigsby, S. J. Burns, L. Giosan, B. Otto-Bliesner, Z. Liu, and J. Zhu. “The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary.” Palaeogeography, Palaeoclimatology, Palaeoecology 415 (December 1, 2014): 3–13. https://doi.org/10.1016/j.palaeo.2014.05.030.
Nace TE, Baker PA, Dwyer GS, Silva CG, Rigsby CA, Burns SJ, et al. The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary. Palaeogeography, Palaeoclimatology, Palaeoecology. 2014 Dec 1;415:3–13.
Nace, T. E., et al. “The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary.” Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 415, Dec. 2014, pp. 3–13. Scopus, doi:10.1016/j.palaeo.2014.05.030.
Nace TE, Baker PA, Dwyer GS, Silva CG, Rigsby CA, Burns SJ, Giosan L, Otto-Bliesner B, Liu Z, Zhu J. The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary. Palaeogeography, Palaeoclimatology, Palaeoecology. 2014 Dec 1;415:3–13.
Journal cover image

Published In

Palaeogeography, Palaeoclimatology, Palaeoecology

DOI

ISSN

0031-0182

Publication Date

December 1, 2014

Volume

415

Start / End Page

3 / 13

Related Subject Headings

  • Paleontology
  • 4301 Archaeology
  • 3709 Physical geography and environmental geoscience
  • 0603 Evolutionary Biology
  • 0602 Ecology
  • 0403 Geology